描述 Description

The SC26C92 is a pin and function replacement for the SCC2692 and SCN2681 with added features and deeper FIFOs. Its configuration on power up is that of the 2692. Its differences from the 2692 are: 8 character receiver, 8 character transmit FIFOs, watch dog timer for each receiver, mode register 0 is added, extended baud rate and overall faster speeds, programmable receiver and transmitter interrupts. (The SCC2692 is not being discontinued.)
The Philips Semiconductors SC26C92 Dual Universal Asynchronous Receiver/Transmitter (DUART) is a single-chip CMOS-LSI communications device that provides two full-duplex asynchronous receiver/transmitter channels in a single package. It interfaces directly with microprocessors and may be used in a polled or interrupt driven system and provides modem and DMA interface.
The operating mode and data format of each channel can be programmed independently. Additionally, each receiver and transmitter can select its operating speed as one of 27 fixed baud rates, a 16X clock derived from a programmable counter/timer, or an external 1X or 16X clock. The baud rate generator and counter/timer can operate directly from a crystal or from external clock inputs. The ability to independently program the operating speed of the receiver and transmitter make the DUART particularly attractive for dual-speed channel applications such as clustered terminal systems.
Each receiver and transmitter is buffered by eight character FIFOs to minimize the potential of receiver overrun, transmitter underrun and to reduce interrupt overhead in interrupt driven systems. In addition, a flow control capability is provided via RTS/CTS signaling to disable a remote transmitter when the receiver buffer is full.
Also provided on the SC26C92 are a multipurpose 7-bit input port and a multipurpose 8-bit output port. These can be used as general purpose I/O ports or can be assigned specific functions (such as clock inputs or status/interrupt outputs) under program control.
The SC26C92 is available in three package versions: 40-pin 0.6\" wide DIP, a 44-pin PLCC and 44-pin plastic quad flat pack (PQFP).

特性 Features

Dual full-duplex independent asynchronous receiver/transmitters
8 character FIFOs for each receiver and transmitter
Programmable data format 5 to 8 data bits plus parity
Odd, even, no parity or force parity
1, 1.5 or 2 stop bits programmable in 1/16-bit increments
16-bit programmable Counter/Timer
Programmable baud rate for each receiver and transmitter selectable from: 27 fixed rates: 50 to 230.4k baud
Other baud rates to 230.4k baud at 16X
Programmable user-defined rates derived from a programmable counter/timer
External 1X or 16X clock
Parity, framing, and overrun error detection
False start bit detection
Line break detection and generation
Programmable channel mode Normal (full-duplex)
Automatic echo
Local loopback
Remote loopback
Multidrop mode (also called ?wake-up? or ?9-bit?)
Multi-function 7-bit input port Can serve as clock, modem, or control inputs
Change of state detection on four inputs
Inputs have typically >100k pull-up resistors
Multi-function 8-bit output port Individual bit set/reset capability
Outputs can be programmed to be status/interrupt signals
FIFO states for DMA and modem interface
Versatile interrupt system Single interrupt output with eight maskable interrupting conditions
Output port can be configured to provide a total of up to six separate wire-ORable interrupt outputs
Each FIFO can be programmed for four different interrupt levels
Watch dog timer for each receiver
Maximum data transfer rates: 1X - 1Mb/sec, 16X - 1Mb/sec
Automatic wake-up mode for multidrop applications
Start-end break interrupt/status
Detects break which originates in the middle of a character
On-chip crystal oscillator
Power down mode
Receiver timeout mode
Single +5V power supply
Powers up to emulate SCC2692